Self-propagating Synthesis Research Articles

A Universal Self-Propagating Synthesis of Aluminum-Based Oxyhalide Solid-State Electrolytes.

Inorganic solid-state electrolytes (SSEs) play a vital role in high-energy all-solid-state batteries (ASSBs). However, the current method of SSE preparation usually involves high-energy mechanical ball milling and/or a high-temperature annealing process, which is not suitable for practical application. Here, a facile strategy is developed to realize the scalable synthesis of cost-effective aluminum-based oxyhalide SSEs, which involves a self-propagating method by the exothermic reaction of the raw materials. This strategy enables the synthesis of various aluminum-based oxyhalide SSEs with tunable components and high ionic conductivities (over 10-3 S cm-1 at 25 °C) for different cations (Li+, Na+, Ag+). It is elucidated that the amorphous matrix, which mainly consists of various oxidized chloroaluminate species that provide numerous sites for smooth ion migration, is actually the key factor for the achieved high conductivities. Benefit from their easy synthesis, low cost, and low weight, the aluminum-based oxyhalide SSEs synthesized by our approach could further promote practical application of high-energy-density ASSBs.

Titanium boride coating by high power diode laser alloying of amorphous boron with titanium and its surface property investigations

Present work deals with fabrication of superhard titanium boride coating on titanium surface with preplaced amorphous boron layer using high power diode laser alloying. Amorphous boron instantaneously converts into crystalline boron by the effect of high-power laser interaction, which rapidly drives the boron species into titanium liquid pool and form titanium boride precipitates by its convective flow. Negative Gibbs free energy (ΔG) and enthalpy (ΔH) of amorphous boron crystallization reaction introduces the concept of laser induced self-propagation synthesis. Gibbs free energy (ΔG) for the chemical reactions between Ti and B was calculated to confirm the spontaneous formation of titanium boride compound phases. The diffusion coefficient and activation energy were estimated to understand the phase formation and microstructural evolution. The structural phase, microstructure, microhardness and wear resistance of the laser borided titanium was investigated by XRD, optical and scanning electron microscopy, EDAX, Vickers microhardness analysis and linear reciprocating wear testing. The laser alloyed coating across the cross section shows formation of dendrites and whisker like microstructures. Average microhardness of 800–1600 HV0.2 was measured at different cross-sectional depths and an extreme hardness of about 3800–4700 HV0.2 was obtained in some regions of boron precipitates. The results showed a high negative value of Gibbs free energy of about −250 kJ/mol and −170 kJ/mol at ∼2000 °C respectively which confirms the spontaneity of TiB2 and TiB phase formation. The activation energy of the titanium boride is estimated to be 140 kJ/mol. The laser borided coating with the formation of TiB and TiB2 phases could be useful for surface engineering applications.

Influence of extrinsic induced tensile stress on the self-propagating high-temperature synthesis of nanosized Al/Ni multilayers

Reactive multilayer systems consisting of alternating nanoscale Al and Ni layers are applicable in joining, various pyrotechnic applications and thermal batteries. Since diffusion based high-temperature synthesis occurs without the presence of air, efforts have focused on investigating the understanding of the fundamental reaction processes and characteristics. The aim of this study is to expose the reactive multilayers to extrinsic induced tensile stress so that the self-propagating synthesis can proceed under these conditions. Further, the properties during and after the reaction will be investigated. Multilayers deposited by sputtering on Kapton® substrates with different bilayer– and total thicknesses as well as commercial Nanofoils® with thicknesses of 40 µm and 60 µm were used as samples. The investigations focused on the propagation velocity measured with a high-speed camera, the temperature regime determined with a high-speed pyrometer, and the formed phases after the synthesis examined via X-ray diffraction. The gained results of this study reveal important insights for the application of the reactive Al/Ni multilayer system in terms of stability or reliability related to propagation front velocity, maximum temperature and formed phases under induced external tensile stresses.Graphical abstract

Influence of the Component Ratio in the Ti–B System on the Structure and Properties of Materials Fabricated by SHS Extrusion

We studied how the ratio of precursor titanium and boron powders influenced the combustion temperature and combustion velocity in the high-temperature self-propagating synthesis (SHS) mode, and the microstructure, phase composition, and mechanophysical properties of rods fabricated by SHS extrusion. The subject matters of the study were materials for which the as-batch phase compositions of products were TiB–(20–40) wt % Ti. The formation of boron solid solution in titanium was considered. Scanning electron microscopy (SEM), X-ray powder diffraction (XRD), and mechanical measurements implied the texture of the prepared materials (TiB whiskers were aligned in the direction in which the external pressure was applied). In all of the composites studied, the conductivity was close to the conductivity of undoped titanium; the electrical resistance increased slightly in response to increasing boron weight fraction. The three-point bending strength of the material increased by a factor of 1.7 at most as the weight fraction of boron solid solution in titanium increased from 20 to 40 wt %.

Self-propagating synthesis of nitrogen-doped graphene as supercapacitor electrode materials

Self-propagating synthesis of nitrogen-doped graphene as supercapacitor electrode materials

OBTAINING AND STUDYING THE PROPERTIES OF IRON AND SILICON-CONTAINING MAX-PHASES BY THE METHOD OF SELF-PROPAGАТING HIGH-TEMPERATURE SYNTHESIS

The paper discusses the preparation and properties of a new class of multifunctional composites, which are obtained by high-temperature self-propagating synthesis (SHS) of various metal powders. The class of such composites includes MAX phases. The aim of this work is to synthesize a MAX-phase of the (Fe,Ti)3(Si,Al)C2 type by self-propagating high-temperature synthesis of a mixture of Ti, FeSi, Al and carbon in equimolar ratios. The synthesized main phase exhibits magnetic properties due to its iron and silicon content. Experiments have shown that from a mixture of powders of ferrosili¬co¬n, titanium, aluminum, carbon by the SHS method, it is possible to obtain a powdery base mass containing 93% of the MAX-phase composition of the type (Fe,Ti)3(Al,Si)C2 by mass, and 7% embedded in rich crystals iron Fe5Si3, Fe3Si and FeSi, which impart magnetic properties to the material, also contain Ti5Si2 and TiC-2% by weight insoluble in the main phase. In order to accurately assess the size distribution of embedded products in the main phase, a new analysis method was chosen - modern automatic microradiographic analysis (MRSA). The principle of the analysis was presented. The microstructure of such a MAX material, synthesized by powder metallurgy (SHS synthesis) methods, has a layered, laminate nature and can become a good raw material for further alloying of this compound with various metals for the development of powder metallurgy in Armenia.

Ti/SiC Based Metal Matrix Composites by Using Self-Propagating High Temperatures Synthesis (SHS)

Ti/SiC Based Metal Matrix Composites by Using Self-Propagating High Temperatures Synthesis (SHS)

Highly Effective Self-Propagating Synthesis of Lamellar ZnO-Decorated MnO2 Nanocrystals with Improved Supercapacitive Performance.

A series of MOx (M = Co, Ni, Zn, Ce)-modified lamellar MnO2 electrode materials were controllably synthesized with a superfast self-propagating technology and their electrochemical practicability was evaluated using a three-electrode system. The results demonstrated that the specific capacitance varied with the heteroatom type as well as the doping level. The low ZnO doping level was more beneficial for improving electrical conductivity and structural stability, and Mn10Zn hybrid nanocrystals exhibited a high specific capacitance of 175.3 F·g−1 and capacitance retention of 96.9% after 2000 cycles at constant current of 0.2 A·g−1. Moreover, XRD, SEM, and XPS characterizations confirmed that a small part of the heteroatoms entered the framework to cause lattice distortion of MnO2, while the rest dispersed uniformly on the surface of the carrier to form an interfacial collaborative effect. All of them induced enhanced electrical conductivity and electrochemical properties. Thus, the current work provides an ultrafast route for development of high-performance pseudocapacitive energy storage nanomaterials.

Research on Microstructure and Properties of TiB<sub>2</sub>/Al-Si Multi-Element Piston Alloy Composite

The Al-12Si-4Cu-2Ni-0.9Mg was used as the matrix, TiB2/Al-12Si-4Cu-2Ni-0.9Mg composite material was prepared by adding Al-TiB2 in master alloy, and the mass fraction of TiB2 particles in the composite material was 3%. TiB2 particles were prepared by melt self-propagating direct synthesis method. Based on studying the influence of mechanical stirring speed on the distribution of TiB2 particles during the preparation of Al-TiB2 master alloy, the optimal mechanical stirring speed was optimized to 800 r/min. TiB2/Al-12Si-4Cu-2Ni-0.9Mg composite material was prepared by remelting and dilution method. The as-cast solidified structure of the composite material was mainly composed of α-Al matrix, Si phase and TiB2 particles, and TiB2 particles were evenly distributed. Under the condition of 360 °C(Working temperature of common piston), the tensile strength of the composite material was 15.4% higher than that of the base material, and the yield strength of the composite material was 29.4% higher than that of the base material.

Self-propagating synthesis of Zn-loaded biochar for tetracycline elimination

Herein, a novel Zn-loaded biochar (Zn-LBC) originating from Fraxinus pennsylvanica Marsh leaves was successfully prepared through a simple and rapid self-propagating combustion reaction (SHS) and could serve as an efficient adsorbent for tetracycline (TC) elimination from water. The adsorption performance was analyzed via a series of characterizations and batch adsorption experiments. The results showed that the novel adsorbent Zn-LBC exhibited an excellent TC adsorption capacity (159.64 mg/g), which was 2.63 times higher than that of the original biochar (60.78 mg/g). The pseudo-second-order kinetic model and Freundlich isothermal model fit the adsorption data well. It is noteworthy that Zn-LBC had little effect on the adsorption capacity of TC in the 0–10 mg/L various coexisting ion range and presence of humic acid (HA). In addition, the adsorption test of TC using hospital wastewater as the water sample also achieved satisfactory results (raw influent: 52.65 mg/g, final effluent: 85.64 mg/g). FT-IR and XPS investigations showed that the TC adsorption mechanism included surface complexation, π-π interactions, and hydrogen bonds. The results provide new ideas for exploring low-cost and highly efficient modified biochar adsorbent for TC elimination.

Preparation of silicon boride SiBx (x = 3, 4, 5, 6) powders by chemical oven self-propagating combustion synthesis

Abstract A new method was developed for quickly preparing a highemissivity silicon boride compound of SiBx (x = 3, 4, 5, 6) by highly exothermic Ti-TiO2-Si-Al chemical oven preheating. The SiBx combustion synthesis process and adiabatic combustion temperature were investigated. A large exothermic reaction occurred at the combustion temperature of 1 700 K. X-ray diffraction results indicate that an SiBx phase and a substantial amount of unreacted Si were identified in the products. By increasing the boron content until the Si-B ratio reached to 1 : 6, the diffraction peaks primarily indicated SiB6, SiB4, and Si11B33 in the final product. According to the spectra and quantitative results, the atomic chemical composition ratio of Si and B was close to the nominal composition. Thus, this method offers an efficient way to produce Si-B compounds with less time and energy consumption than current methods.

Preparation of silicon boride SiBx (x = 3, 4, 5, 6) powders by chemical oven self-propagating combustion synthesis

Abstract A new method was developed for quickly preparing a highemissivity silicon boride compound of SiBx (x = 3, 4, 5, 6) by highly exothermic Ti-TiO2-Si-Al chemical oven preheating. The SiBx combustion synthesis process and adiabatic combustion temperature were investigated. A large exothermic reaction occurred at the combustion temperature of 1 700 K. X-ray diffraction results indicate that an SiBx phase and a substantial amount of unreacted Si were identified in the products. By increasing the boron content until the Si-B ratio reached to 1 : 6, the diffraction peaks primarily indicated SiB6, SiB4, and Si11B33 in the final product. According to the spectra and quantitative results, the atomic chemical composition ratio of Si and B was close to the nominal composition. Thus, this method offers an efficient way to produce Si-B compounds with less time and energy consumption than current methods.

Self-propagating synthesis joining of Cf/Al composites and TC4 alloy using AgCu filler with Ni–Al–Zr interlayer

The successful joining of carbon fiber-reinforced aluminum matrix (Cf/Al) composites and TC4 alloy can produce composite structure and meet the demands of lightweight in aerospace field. Up to now, few experimental researches have been reported on the joining of Cf/Al composites and TC4 alloy. In this study, the AgCu foils and Ni–Al–Zr compact were designed for the self-propagating high-temperature synthesis joining of these two materials. Cf/Al composites were joined with a reactive Ti plated on its joining surface. The typical microstructure of TC4/(AgCu/Ni–Al–Zr/AgCu)/Ti/Cf/Al joint was analyzed, and the effects of joining condition on microstructural evolution of the SHS joint were investigated. A thin reaction layer of Ni–Al–Ti intermetallic compounds was formed adjacent to the TC4 alloy. As a result, AgCu foils could reduce the effect of reaction heat on the substrates and improve the joint shear strength. When the thickness of AgCu foils reaches 150 μm, the Ni–Al–Zr interlayer mainly acts as auxiliary heat source. High joining pressure caused the active elements to diffuse into Cf/Al composites and weakened the shear strength of the joint. Finally, the joint shear strength could reach 36.4 MPa when the AgCu foils were 50 μm and the joining pressure was 2 MPa.

Methods of the Synthesis of Aluminum Borides from Elemental Substances for Use as High-Energy Materials: A Review

Two methods of the synthesis of aluminum borides are considered, one of which is the calcination of a mixture of Al and B powders at temperatures from 900 to 1500°C and the other is high-temperature self-propagating synthesis with mechanical preactivation. It is shown that aluminum borides can be synthesized by mechanical activation alone. All these methods give micrometer-sized particles of aluminum borides. The plasma recondensation of an Al–B mixture produces nanodispersed powders of aluminum borides. The activity of the powders with respect to atmospheric oxygen is determined by thermogravimetric analysis.

Study on reaction productions and morphology of Al-Ti-C-SiC master alloy in self-propagating high temperature synthesis

Al-Ti-C-SiC master alloys were prepared by self-propagating high-temperature synthesis method with the aluminum powder, titanium powder, graphite powder and nano-SiC powder. The reaction productions and morphology of Al-Ti-C-SiC master alloy were systematically investigated. The results show that with the addition of SiC nano-particles, the reaction sequence of self-propagation synthesis of Al-Ti-C alloy was changed. During the reaction, the SiC nano-particles reacts with the titanium powder, which leads to an increase amounts of the TiC particles, In the self-propagation products of Al-Ti-C-SiC system, the size of TiC particles decreases first and then increases with the increase of SiC nano-particles mass fraction. When the mass fraction of SiC nano-particles is 10%, the size of TiC particles becomes nanometre, which size reach 100nm-200nm. When the mass fraction of SiC nano-particles is more than 10%, SiC nano-particles can be found in the master alloy product.

Synthesis of the nickel-containing catalyst on the aluminum oxide supporter produced by glycine-nitrate synthesis

Nanosized aluminum oxide is actively used to produce highly effective catalysts. There are a large number of methods for its preparation. One of the simplest methods for producing oxide materials is high-temperature self-propagating synthesis. To increase the degree of precursors mixing in the synthesis, water-soluble compounds were used: aluminum nitrate (oxidizing agent) and glycine (fuel). The produced aluminum oxide was calcined and impregnated with nickel nitrate and re-calcined. The catalyst was studied by X-ray phase analysis, IR spectroscopy, BET method (specific surface analysis), scanning electronic microscopy and pH measurement (Hammett acidity functions). In this case, the specific surface of the sample synthesized by the glycine-nitrate synthesis method after impregnation with a 5% solution of nickel nitrate sharply increased (16.5–336.6 m2/g). It was established that, before impregnation with nickel oxide, acid centers predominate on the surface of aluminum oxide, and after impregnation, the main ones. Hammett's acidity function was 10.7. Despite the fact that the catalyst has an average catalytic activity in a standardized oxidation of hydrogen, it has the necessary number of acidic and basic centers, which expands the possibilities of its modification and deposition of catalytically active components.

Окислительная фотокаталитическая деструкция эозина с применением железосодержащих металлокерамических композитов с добавкой комплексообразующих реагентов

Iron-containing metal-ceramic composites based on nitrogen and sialon nitrides, obtained by the method of self-propagated synthesis were studied in the process of photocatalytic oxidative destruction of eosin. The phase composition of the samples was established by the X-ray diffraction method. It was shown that, along with the main phases, the ceramic matrix of materials contains the phases of semiconductors: (SiC, TiN). The indicator method of Hammet and Tanabe assessed the surface acid-base centers of the composites. It was established that a large sorption of the dye is characteristic of samples based on silicon nitride and sialon and is associated with the participation of active Brensted acid sites. The photocatalytic activity of iron-containing composites was studied in the presence of H2O2 (photo-Fenton system), H2O2 and EDTA (peroxide-ferriccomplexon system), H2O2 and tartaric acid (peroxide-ferritartrate system). It was shown that the degree of oxidative destruction of eosin is significantly higher with the participation of Fe(II, III) complexes with EDTA and tartaric acid, than Fe(II, III) aquacomplexes in the photo-Feton system. The high activity of composites containing the semiconductor phase of titanium nitride (TiN) is due to the combination of homogeneous and heterogeneous catalysis with the participation of the ceramic matrix. The introduction of complexing agents shifts the optimal acidity (pH 2-4) for a homogeneous system of photo-Fenton with the participation of iron(II, III) aqua complexes in the weakly acidic region (pH 4-7) and leads to almost complete destruction of the dye in the peroxide-tartrate system.

Effect of Synthesis Mode and Ni Particle Size on Microstructural Aspects and Hardness Properties of Combustion-Synthesized NiTi

NiTi intermetallic compound was fabricated via two modes of the combustion synthesis process, namely, thermal explosion (TE) and self-propagating synthesis (SHS). The effect of combustion synthesis mode as well as Ni particle size on the microstructure and microhardness of the final products was investigated. The phases in the products were determined using XRD technique, and microstructural investigations were performed using optical as well as SEM-EDS in order to make a comparison between microstructural evolutions in each mode, other conditions being constant. The analyses showed that the desired B2(NiTi) was successfully formed as the primary phase in all samples, and no unreacted Ni or Ti powders were present. The main secondary phase was NiTi2 which was invariably present in all samples; however, the percentage as well as the morphology of the detrimental NiTi2 phase was found out to be controllable by the mode of combustion as well as Ni particle size. A comparison between the two modes revealed that samples produced by TE showed coarse dendrites in the microstructure; they also presented higher average microhardness values. The SHS-synthesized samples exhibited microstructures similar to those observed in heat-treated and homogenized NiTi obtained from methods such as vacuum arc remelting and vacuum induction melting, and contained finely dispersed NiTi2 particles. It was shown that a decrease in Ni particle size presented a grain refining effect on NiTi2 in both modes.

Mechanical properties of high density MgAl2O4/TiC/W composite prepared via self-propagating synthesis with direct consolidation technique

MgAl2O4-TiC/W composite has been successfully insitu synthesized in a high dense form using combustion synthesis under-load technology. The process was applied to a blend of titanium dioxide, carbon magnesium oxide, aluminum metal and tungsten carbide powders. The different parameters affecting the synthesis of the target composite were investigated. This included the effect of aluminium particle size (37, 18.2, 5.6 μm), carbon stoichiometry (0.7–0.9), WC wt% (10–30 wt%). The obtained results showed that, 18.2 μm Al, 0.8 carbon stoichiometry and 234 MPa load were necessary to obtain high dense composite 2.4 vol% porosity and hardness of 1535 HV with homogeneous microstructure. Addition of 20 wt% WC highly improved the microstructure and the sample hardness was increased to 1754 HV with a sample porosity of ∼3.0 vol%. Thermodynamic study of the different reactions involved in the combustion process was also conducted.

Biocompatibility of Porous SHS-TiNi

Implants made of porous SHS-TiNi alloys are successfully used in medicine to replace solid tissues of the human body. Self-propagating synthesis reaction of TiNi alloy was carried out through layer-by-layer combustion. XRD analysis of the phase composition and structural parameters of porous Ni50Ti50 alloy, as well as microscopic studies, were carried out. The structural methods employed in the study showed that the surface of porous SHS-TiNi alloys is a complex of dense layers of amorphous-nanocrystalline intermetallic oxycarbonitrides saturated with O, N, C intercalation impurities. The study of the surface layer S showed that the layer S consists of three layers: the foam layer F and two sublayers. Samples were studied for the nonuniform potential distribution in the cross section of interpore partitions. It was shown that they correlate with the structural phase inhomogeneity of the SHS-TiNi alloy. The structural studies carried out using different methods allowed us to reliably establish the presence of surface nonmetallic phases in the form of surface films and grain boundary inclusions formed during the self-propagating reaction synthesis of the porous TiNi alloy. High biochemical compatibility is ensured by specific surface layers of the porous alloy formed in the process of its metallurgy, which do not require additional surface modification.